Thermosetting compositions, coating compositions method of coating, and coated articles

ABSTRACT

A thermosetting composition which gives a cured product having excellent weatherability, chemical and physical properties, in particular acid resistance and abrasion resistance, at a relatively low temperature, which has superior storage stability, and which can be used as a one component coating material; a coating composition utilizing this thermosetting composition; a method of coating; and a coated article are provided. The thermosetting composition contains a resin having at least one functional group selected from the group consisting of a blocked hydroxyl group, blocked carboxylic acid, and an epoxy group. The thermosetting composition has a blocked hydroxyl group, blocked carboxylic acid, and an epoxy group.

FIELD OF THE INVENTION

The present invention relates to thermosetting compositions, coatingcompositions, method of coating, and coated articles. More specifically,the present invention relates to thermosetting compositions having ablocked hydroxyl group, blocked carboxylic acid, and an epoxy group, allof which are functional groups; coating compositions having excellentstorage stability and providing coating films with superior chemical andphysical properties such as acid resistance and abrasion resistance, aswell as excellent weatherability; and a method of coating and coatedarticles using such coating compositions and having excellent appearanceof the finished coating.

BACKGROUND OF THE INVENTION

In the field of thermosetting coating materials including those forautomobiles, cross-liked coating materials employing amino resins suchas melamine resins as a hardening agent have typically been used for along time due to the excellent appearance and weatherability of theresulting coating films, as well as stability and economical efficiency.Recently, however, it has been revealed that coating films havingmelamine type cross-linking are suffered from depressed water spots(etching) which cannot be washed off with water, which has become aserious problem. Further, as the number of automobiles coated withdark-hued coating materials has been increasing, scratches made withbrushes in washing have also been a remarkable problem. Accordingly,coating materials for automobiles having superior abrasion resistanceagainst scratches are strongly demanded.

In order to overcome these problems, compositions having varioushardening systems have been proposed. For example, Japanese Laid-openPatent Application No. 51-114429, EP-A-29 595, U.S. Pat. Nos. 4,371,667,4,650,718, 4,618,811, 4,703,101, and 4,764,430 disclose compositionsincluding a combination of a carboxyl group and an epoxy group.

U.S. Pat. No. 3,505,297, Japanese Laid-open Patent Application Nos.60-88038 and 2-115238 disclose compositions including a combination of acarboxyl group and an oxazoline group.

These thermosetting compositions give cured products having excellentchemical and physical properties as well as weatherability, and arewidely utilized in the fields of coating materials, inks, adhesives, andmolded plastics.

However, reactivity between the carboxyl group and the above-mentionedreactive functional groups is so high that compositions containing botha compound having a carboxyl group and a compound having such reactivefunctional groups are often gelled during storage and the periodsuitable for the service of the compositions is short.

Compounds having a carboxyl group used for the conventionalthermosetting compositions have drawbacks that their solubility ingenerally used organic solvents is low and that their compatibility withthe compounds having functional groups reactive with a carboxyl group isinferior, since the carboxyl group has a strong hydrogen bond. Thus,when the thermosetting compositions containing such compounds are usedas a top coating material, it is difficult to prepare high solid coatingmaterials, and appearance of the finished coating is inferior.

Japanese Laid-open Patent Application No. 3-172318 discloses a coatingfilm produced by curing a coating composition containing a blockedhydroxyl group, an acid anhydride group, an epoxy group, and ahydrolytic silyl group. This coating film has excellent acid resistanceand abrasion resistance and thus is useful, but the storage stability ofthe coating material is not sufficiently high.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide thermosettingcompositions and coating compositions containing such compositions,which give cured products having excellent weatherability as well aschemical and physical properties, in particular superior acid resistanceand abrasion resistance, at a relatively low temperature, which exhibitexcellent storage stability, and which may be used as one componentcoating compositions.

It is another object of the present invention to provide a method ofcoating which discharges only a small amount of organic solvents andwhich gives excellent appearance to the finished coating, and coatedarticles obtained by such a method.

The present inventors have made intensive investigations for developingthermosetting compositions which give coating compositions having theabove-mentioned desired properties. As a result, they have discoveredthat compounds having, as functional groups, (1) ablockedhydroxyl groupobtained by reacting polymerizable unsaturated monomers having ahydroxyl group with either a vinyl ether group or a heterocyclic grouphaving a vinyl type double bond and an oxygen atom as the hetero atom,(2) blocked carboxylic acid obtained by reacting a carboxylic acidcompound with a vinyl ether group, a vinyl thioether group, or aheterocyclic group having a vinyl type double bond and an oxygen orsulfur atom as the hetero atom, and (3) an epoxy group, and use of athermal latent catalyst which is activated during curing by heating,will give coating compositions giving superior storage stability to thecoating materials and superior abrasion resistance and acid resistanceto the cured products, thereby completing the present invention.

According to the present invention, there is provided a thermosettingcomposition comprising a resin having at least one functional groupselected from the group consisting of a blocked hydroxyl group, blockedcarboxylic acid, and an epoxy group, said composition having a blockedhydroxyl group, blocked carboxylic acid, and an epoxy group.

According to the present invention, there is also provided a coatingcomposition comprising the above-mentioned thermosetting composition anda thermal latent catalyst activated during curing by heating.

According to the present invention, there is further provided a methodof coating an article comprising the steps of applying theabove-mentioned coating composition over an article to be coated, andcuring the applied coating composition by heating to form a coating filmover the article.

According to the present invention, there is also provided a coatedarticle coated by the above method.

PREFERRED EMBODIMENTS OF THE INVENTION

The blocked hydroxyl group in the present invention may have thestructure represented by the formula (1) or (2) below: ##STR1## whereinR¹ stands for a hydrogen atom or an alkyl group having 1 to 10 carbonatoms, R² stands for an alkyl group having 1 to 22 carbon atoms in whichhydrogen is substituted or not substituted by at least one memberselected from the group consisting of a cycloalkyl group, an aralkylgroup, an aryl group, an alkoxyl group, an alkanoyloxy group, an alkylgroup having 1 to 18 carbon atoms, and a halogen atom; ##STR2## whereinX stands for an alkylene group having 1 to 18 carbon atoms in whichhydrogen is substituted or not substituted by at least one memberselected from the group consisting of an alkoxyl group, an aralkylgroup, an aryl group, an aryloxy group, an alkanoyloxy group, an alkylgroup having 1 to 10 carbon atoms, and a halogen atom.

Examples of compounds including the structure represented by the formula(1) may include 1-alkoxy-ethoxyethyl (meth)acrylates such as1-methoxy-ethoxyethyl (meth)acrylate, 1-ethoxy-ethoxyethyl(meth)acrylate, 1-butoxy-ethoxyethyl (meth)acrylate,1-(2-ethylhexanoxy)-ethoxyethyl (meth)acrylate, 1-isobutoxy-ethoxyethyl(meth)acrylate, or 1-cyclohexyloxy-ethoxyethyl (meth)acrylate.

The compound including the structure represented by the formula (1)maybe a compound obtained by adding alkyl vinyl ethers to the hydroxylgroup in the polymerizable unsaturated monomers having a hydroxyl group,but is not limited thereto. For example, a compound including astructure obtained by adding ε-caprolactone to N-methylol(meth)acrylamide or β-hydroxyethyl (meth)acrylate, or a compoundincluding a structure obtained by adding a vinyl ether compound to(meth)acrylates of polyoxyalkylene glycol may also be used. The vinylether compound subjected to the above addition reaction may be aliphaticvinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether,isopropyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether,isobutyl vinyl ether, 2-ethylhexyl vinyl ether, or cyclohexyl vinylether. Further, the compound including the structure of (1) may be acompound including a structure obtained by adding a vinyl ether compoundto a hydroxyl group in polyester polyol, polyether polyol, or acrylpolyol.

Monomers including the structure represented by the formula (2) maytypically be compounds represented by the formulae below: ##STR3##

The monomer including the structure represented by the formula (2) maybe a compound including a structure obtained by adding a heterocycliccompound having a vinyl type double bond and an oxygen atom as thehetero atom to the hydroxyl group in an unsaturated monomer having ahydroxyl group, but is not limited thereto. For example, a compoundobtained by adding ε-caprolactone to N-methylol (meth)acrylamide orβ-hydroxyethyl (meth)acrylate; or a compound including a structureobtained by adding a heterocyclic compound having a vinyl type doublebond and an oxygen atom as the hetero atom to (meth)acrylates ofpolyoxyalkylene glycol may also be used. The heterocyclic compoundhaving a vinyl type double bond and an oxygen atom as the hetero atomsubjected to the above addition reaction may be a cyclic vinyl ethercompound such as 2,3-dihydrofuran, 3,4-dihydrofuran,2,3-dihydro-2H-pyrane, 3,4-dihydro-2H-pyrane,3,4-dihydro-2-methoxy-2H-pyrane,3,4-dihydro-4,4-dimethyl-2H-pyrane-2-one,3,4-dihydro-2-ethoxy-2H-pyrane, or sodium salt of3,4-dihydro-2H-pyrane-2-carboxylic acid. Further, the monomer includingthe structure of (2) maybe a compound including a structure obtained byadding a heterocyclic compound having a vinyl type double bond and anoxygen atom as the hetero atom to the hydroxyl group in polyesterpolyol, polyether polyol, or acryl polyol.

The blocked carboxylic acid in the present invention may have thestructure represented by the formula (3) ##STR4## wherein R³ R⁴, and R⁵each stands for a hydrogen atom or an organic residue having 1 to 18carbon atoms, and R⁶ stands for an organic residue having 1 to 18 carbonatoms. R and R6 may be bound together to form a heterocyclic ring havingY as the hetero atom, wherein Y stands for an oxygen or sulfur atom.

Polymerizable unsaturated monomers containing the blocked carboxylicacid represented by the formula (3) as the functional group may easilybe obtained by reacting a compound having a carboxyl group with an alkylvinyl ether compound, an alkyl vinyl thioether compound correspondingthereto, or a heterocyclic compound having a vinyl type double bond andan oxygen or sulfur atom as the hetero atom. This reaction is usuallyproceeded in the presence of an acid catalyst at a temperature within arange from a room temperature to 100° C.

Examples of the compound having a carboxyl group may include aliphaticpolycarboxylic acid having 2 to 22 carbon atoms such as succinic acid,adipic acid, azelaic acid, sebacic acid, or decamethylenedicarboxylicacid; aromatic polycarboxylic acid such as phthalic acid, isophthalicacid, terephthalic acid, trimellitic acid, or pyromellitic acid;alicyclic polycarboxylic acid such as tetrahydrophthalic acid,hexahydrophthalic acid, or methylhexahydrophthalic acid; a polyesterresin, acrylic resin, or a maleinated polybutadiene resin, each having acarboxyl group.

Each of the thermosetting composition and the coating composition of thepresent invention (collectively referred to as "composition"hereinafter) contains one or more resins having at least one functionalgroup selected from the group consisting of a blocked hydroxyl group,blocked carboxylic acid, and an epoxy group, and the compositionincludes a blocked hydroxyl group, blocked carboxylic acid, and an epoxygroup as requisite functional groups. Therefore, the resin which may becontained in the composition may be a resin having one of the blockedhydroxyl group, the blocked carboxylic acid, and the epoxy group; or aresin having two or three of the blocked hydroxyl group, the blockedcarboxylic acid, and the epoxy group. The resin may preferably be anacrylic resin having the number average molecular weight of 500 to100000 or a polyester resin having the number average molecular weightof 500 to 100000. Specifically, an acrylic rein having the numberaverage molecular weight of 500 to 100000 and having at least onefunctional group selected from the group consisting of a blockedhydroxyl group, blocked carboxylic acid, and an epoxy group; a polyesterresin having the number average molecular weight of 500 to 100000 andhaving a blocked hydroxyl group and/or blocked carboxylic acid; ormixtures thereof may be used.

The acrylic resin having the number average molecular weight of 500 to100000 and having at least one of the above functional groups may be apolymer of polymerizable unsaturated monomers containing the blockedhydroxyl group; polymerizable unsaturated monomers containing theblocked carboxylic acid; polymerizable unsaturated monomers containingthe epoxy group such as glycidyl (meth)acrylate,3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethylmethacrylate; or mixtures thereof; or a polymer of one or more of thesemonomers and other α, β-unsaturated monomers, each obtained byconventional radical polymerization under suitably selected conditions.Examples of the above-mentioned other α, β-unsaturated monomers mayinclude methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, n-propyl acrylate, n-propyl methacrylate, isopropylacrylate, isopropyl methacrylate, n-butyl acrylate, n-butylmethacrylate, isobutyl acrylate, isobutyl methacrylate, sec-butylacrylate, sec-butyl methacrylate, cyclohexyl acrylate, cyclohexylmethacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearylacrylate, stearyl methacrylate, lauryl acrylate, lauryl methacrylate,styrene, α-methylstyrene, p-vinyltoluene, or acrylonitrile.

The acrylic resin having the number average molecular weight of 500 to100000 and having at least one of the above functional groups may alsobe obtained by radical polymerization of polymerizable unsaturatedmonomers containing a hydroxyl group, unsaturated monomers containing acarboxyl group, polymerizable unsaturated monomers containing an epoxygroup, or mixtures thereof, and optionally with other α, β-unsaturatedmonomers, and then blocking the hydroxyl group and the carboxylic acidtherein according to the method as mentioned above.

The polyester resin having the number average molecular weight of 500 to100000 and having the above functional groups may be obtained bysynthesizing a polyester resin using a desired mole ratio of polybasicacid to a polyhydric alcohol in accordance with the conventionalsynthesis process to obtain a polyester resin having hydroxyl groupand/or carboxyl group terminals of a desired concentration, and thenblocking the hydroxyl group and carboxylic acid in the polyester resinin accordance with the above method.

Examples of the polybasic acid used for preparing the polyester resinmay include aliphatic polycarboxylic acid having 2 to 22 carbon atomssuch as succinic acid, adipic acid, azelaic acid, sebacic acid, ordecamethylenedicarboxylic acid; aromatic polycarboxylic acid such asphthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, orpyromellitic acid; alicyclic polycarboxylic acid such astetrahydrophthalic acid, or hexahydrophthalic acid; or acid anhydridesuch as succinic anhydride, maleic anhydride, phthalic anhydride,tetrahydrophthalic anhydride, tetrabromophthalic anhydride,tetrachlorophthalic anhydride, hexahydrophthalic anhydride, trimelliticanhydride, or pyromellitic anhydride.

Examples of the polyhydric alcohol for preparing the polyester resin mayinclude alcohols such as ethylene glycol, 1,2-propylene glycol,1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol,1,6-hexanediol, diethylene glycol, pentanediol, dimethylbutanediol,hydrogenated bisphenol A, glycerine, sorbitol, neopentyl glycol,1,8-octanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol,1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylolethane,trimethylolpropane, pentaerythritol, quinitol, mannitol,trishydroxyethyl isocyanurate, or dipentaerythritol; addition productsof these polyhydric alcohols with a lactone compound such asγ-butyrolactone or ε-caprolactone by ring opening of the lactone;addition products of these polyhydric alcohols with an isocyanatecompound such as tolylene diisocyanate, diphenylmethane diisocyanate,hexamethylene diisocyanate, or isophorone diisocyanate in excess amountof the alcohol; addition products of these polyhydric alcohols with avinyl ether compound such as ethylene glycol divinyl ether, polyethyleneglycol divinyl ether, butanediol divinyl ether, pentanediol divinylether, hexanediol divinyl ether, or 1,4-cyclohexanedimethanol divinylether in excess amount of the alcohol; or condensation products of thesepolyhydric alcohols with an alkoxysilicon compound such as KR-213,KR-217, KR-9218 (trade names, manufactured by Shinetsu Chemical Co.,Ltd.) in excess amount of the alcohol. Further, silicon oils containinga hydroxyl group such as X-22-160AS, KF-6001 (trade names, manufacturedby Shinetsu Chemical Co., Ltd.) may also be used.

The acrylic resin and the polyester resin preferably have the numberaverage molecular weight of 500 to 100000, as discussed above. If thenumber average molecular weight is less than 500, a large portion of thecomponents does not have the functional groups and thus functions like aplasticizer to cause poor coating film properties such as lowweatherability and moisture resistance, and inferior abrasionresistance, thus being not preferred. If the number average molecularweight exceeds 100000, the viscosity of the resin becomes exceedinglyhigh, the amount of the nonvolatile components in the thermosettingcomposition at a suitable viscosity for coating becomes less, and thestorage stability of the coating material is lowered, thus being notpreferred.

In the composition of the present invention, the concentration of theblocked carboxylic acid as the functional group in the composition ispreferably 0.5 to 4 mol/kg, more preferably 1 to 3 mol/kg based on thetotal solid content of the reactive resins in the composition. If theconcentration of the functional group is less than 0.5 mol/kg, a curedfilm having sufficient cross-linking density cannot be obtained, andchemical resistance such as acid resistance, physical properties such asabrasion resistance, and weatherability of the film become poor, thusbeing not preferred. If the concentration of the functional groupexceeds 4 mol/kg, the functional groups which do not participate in thecuring reaction will remain, which adversely affects the chemicalproperties of the cured film, thus being not preferred.

The concentration of the blocked hydroxyl group as the functional groupin the composition is preferably 0.05 to 2 mol/kg, more preferably 0.1to 1.5 mol/kg based on the total solid content of the reactive resins inthe composition. If the concentration of the functional group is lessthan 0.05 mol/kg, a cured film having sufficient cross-linking densitycannot be obtained, and thus the physical properties such as abrasionresistance of the film become poor, thus being not preferred. If theconcentration of the functional group exceeds 2 mol/kg, functionalgroups which do not participate in the curing reaction will remain,which adversely affects the chemical properties of the cured film, thusnot being preferred.

The concentration of the epoxy group as the functional group in thecomposition is preferably 0.5 to 4 mol/kg, more preferably 1 to 3 mol/kgbased on the total solid content of the reactive resins in thecomposition. If the concentration of the functional group is less than0.5 mol/kg, a cured film having sufficient cross-linking density cannotbe obtained, and chemical resistance such as acid resistance, physicalproperties such as abrasion resistance, and weatherability of the filmbecome poor, thus not being preferred. If the concentration of thefunctional group exceeds 4 mol/kg, functional groups which do notparticipate in the curing reaction will remain, which adversely affectsthe chemical properties of the cured film, thus not being preferred.

Preferred ratio of the blocked hydroxyl group, the blocked carboxylicacid, and the epoxy group as the functional groups in the composition ofthe present invention is the blocked carboxylic acid/the epoxy group=0.5 to 1.5, more preferably 0.8 to 1.2, and the blocked hydroxylgroup/the epoxy group =0.02 to 1.5, more preferably 0.1 to 1.0 in moleratio.

The coating composition of the present invention contains a thermallatent acid catalyst which is activated during curing by heating for thepurpose of maintaining excellent storage stability of the compositionfor a prolonged period of time, accelerating the curing reaction forcuring the composition at a low temperature in a short time, and givingexcellent chemical and physical properties to the cured product. Thethermal latent acid catalyst may preferably exhibit acid catalyticactivity at 60° C. or higher temperature. If the thermal latent acidcatalyst exhibits the acid catalytic activity at a temperature lowerthan 60° C., the viscosity of the resulting composition will increaseduring storage and is likely to be gelled.

Examples of the thermal latent acid catalyst may preferably include acompound obtained by neutralizing protonic acid with Lewis base; acompound obtained by neutralizing Lewis acid with Lewis base; a mixtureof Lewis acid and trialkyl phosphate; sulfonates; phosphates; and oniumcompounds.

Examples of the compound obtained by neutralizing protonic acid withLewis base may include compounds obtained by neutralizinghalogenocarboxylic acids, sulfonic acids, monoesters of sulfuric acid,monoesters or diesters of phosphoric acid, esters of polyphosphoricacid, monoesters or diesters of boric acid, with various kinds of aminessuch as ammonia, monoethylamine, triethylamine, pyridine, piperidine,aniline, morpholine, cyclohexylamine, n-butylamine, monoethanolamine,diethanolamine, or triethanolamine, trialkylphosphine, triarylphosphine,trialkylphosphite, ortriarylphosphite. Alternatively, Nacure 2500X,X-47-110, 3525, 5225 (trade names, manufactured by King Industries Co.,Ltd.) marketed as a catalyst of acid-base adduct may also be used.

Examples of the Lewis acid used for preparing the compound obtained byneutralizing Lewis acid with Lewis base may include metal halides suchas boron trifluoride, aluminum trichloride, titanium trichloride,titanium tetrachloride, ferrous chloride, ferric chloride, zincchloride, zinc bromide, stannous chloride, stannic chloride, stannousbromide, or stannic bromide; organometal compounds such astrialkylboron, trialkylaluminum, dialkylaluminum halide,monoalkylaluminum halide, or tetraalkyltin; metal chelate compounds suchas diisopropoxyethyl acetoacetate aluminum, tris(ethyl acetoacetate)aluminum, isopropoxybis(ethyl acetoacetate) aluminum,monoacetylacetonatobis(ethyl acetoacetate) aluminum, tris(n-propylacetoacetate) aluminum, tris(n-butyl acetoacetate) aluminum, monoethylacetoacetate· bis(acetylacetonato)aluminum,tris(acetylacetonato)aluminum, tris(propionylacetonato)aluminum,acetylacetonato· bis(propionylacetonato)aluminum, diisopropoxybis(ethylacetoacetate) titanium, diisopropoxybis(acetyl acetoacetate) titanium,tetrakis(n-propyl acetoacetate) zirconium,tetrakis(acetylacetonato)zirconium, tetrakis(ethyl acetoacetate)zirconium, dichloro· bis(acetylacetonato)tin, dibutyl·bis(acetylacetonato)tin, tris(acetylacetonato)iron,tris(acetylacetonato)chromium, tris(acetylacetonato)rhodium,bis(acetylacetonato)zinc, or tris(acetylacetonato)cobalt; or organicmetal soaps such as dibutyltin dilaurate, dioctyltin ester maleate,magnesium naphthenate, calcium naphthenate, manganese naphthenate, ironnaphthenate, cobalt naphthenate, copper naphthenate, zinc naphthenate,zirconium naphthenate, lead naphthenate, calcium octanoate, manganeseoctanoate, iron octanoate, cobalt octanoate, zinc octanoate, zirconiumoctanoate, tin octanoate, lead octanoate, zinc laurate, magnesiumstearate, aluminum stearate, calcium stearate, cobalt stearate, zincstearate, or lead stearate.

Examples of the Lewis base may include amines such as ammonia,triethylamine, pyridine, aniline, morpholine, N-methylmorpholine,pyrrolidine, N-methylpyrrolidine, piperidine, N-methylpiperidine,cyclohexylamine, n-butylamine, dimethyloxazoline, imidazole,N-methylimidazole, N,N-dimethylethanolamine, N,N-dimethylethanolamine,N,N-dipropylethanolamine, N,N-dibutylethanolamine,N,N-dimethylisopropanolamine, N,N-diethylisopropanolamine,N,N-dipropylisopropanolamine, N,N-dibutylisopropanolamine,N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine,N-butyldiethanolamine, N-methyldiisopropanolamine,N-ethyldiisopropanolamine, N-propyldiisopropanolamine, triethanolamine,triisopropanolamine, or tri-s-butanolamine; amides such asN,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, orhexamethylphosphoric acid triamide; sulfoxide compounds such as dimethylsulfoxide; compounds having an ether bond such as diethyl ether ortetrahydrofuran; alkyl sulfides such as dimethyl sulfide, diethylsulfide, di-n-propyl sulfide, di-n-butyl sulfide, di-n-hexyl sulfide,diisopropyl sulfide, di-sec-butyl sulfide, di-tert-butyl sulfide,di-n-octyl sulfide, or di-2-ethylhexyl sulfide; hydroxyalkyl sulfidessuch as 2-(ethylthio)ethanol, 2,2'-thiodiethanol, or bis(2-methoxyethyl)sulfide, or derivatives thereof; sulfur-containing compounds having anaromatic ring such as diphenyl sulfide or thioanisol; sulfur-containingcompounds having carboxylate such as methyl methylthioacetate, ethylmethylthiopropionate, or dimethyl thiodipropionate, sulfur-containingcompounds having a nitrile group such as thiodipropionitrile; orcompounds such as tetrahydrothiophene, tetrahydrothiopyran,1,2-oxathiolane, 1,3-oxathiolane, 1,3-oxathiane, or 1,4-oxathiane.

The Lewis acid used for preparing the mixture of Lewis acid and trialkylphosphate may be the Lewis acids as listed above.

The sulfonates may be compounds represented by the formula (4): ##STR5##wherein R¹⁰ stands for a phenyl group, a substituted phenyl group, anaphthyl group, a substituted naphthyl group, or an alkyl group, R¹¹stands for an alkyl group having 3 to 18 carbon atoms, an alkenyl group,an aryl group, an alkalyl group, an alkanol group, a saturated orunsaturated cycloalkyl group, or hydroxycycloalkyl group, each bound toa sulfonyloxy group via a primary or secondary carbon.

Examples of the sulfonates represented by the formula (4) may includesulfonic acids such as methanesulfonic acid, ethanesulfonic acid,benzenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonicacid, or nonylnaphthalenesulfonic acid, esterified with primary alcoholssuch as n-propanol, n-butanol, n-hexanol, or n-octanol, or secondaryalcohols such as isopropanol, 2-butanol, 2-hexanol, 2-octanol, orcyclohexanol; or β-hydroxyalkyl sulfonates obtained by reacting theabove-mentioned sulfonic acid with compounds containing an oxiranegroup.

The phosphates may include a compound represented by the formula (5).##STR6## wherein R¹² stands for an alkyl group having 3 to 10 carbonatoms, a cycloalkyl group, or an aryl group, and n is an integer of 1 or2.

Examples of the phosphates represented by the formula (5) may includephosphoric monoesters or diesters of primary alcohols such asn-propanol, n-butanol, n-hexanol, n-octanol, or 2-ethylhexanol, or thoseof secondary alcohols such as isopropanol, 2-butanol, 2-hexanol,2-octanol, or cyclohexanol.

The onium compounds may include compounds represented by the formula[(R¹³)₃ NR¹⁴ ]⁺ X⁻, [(R¹³)₃ PR¹⁴ ]⁺ X⁻, [(R¹³) ₃ OR¹⁴ ]⁺ X⁻, or [(R¹³)₃SR¹⁴ ]⁺ X⁻, wherein R stands for an alkyl group having 1 to 12 carbonatoms, an alkenyl group, an aryl group, an alkalyl group, an alkanolgroup, or a cycloalkyl group, wherein two of R¹³ may be bound togetherto form a heterocyclic ring having N, P, O, or S as the hetero atom, andwherein R¹⁴ stands for a hydrogen atom, an alkyl group having 1 to 12carbon atoms, an alkenyl group, an aryl group, or an alkalyl group, X⁻stands for SbF₆ ⁻, AsF₆ ⁻, PF₆ ⁻, or BF₄ ⁻.

The coating composition of the present invention may contain one or morekinds of thermal latent acid catalysts. The content of the thermallatent acid catalyst may usually be 0.01 to 20 parts by weight,preferably 0.02 to 10 parts by weight based on 100 parts by weight ofthe total solid content of the coating composition. If the content ofthe catalyst is less than 0.01 parts by weight based on 100 parts byweight of the total solid content, the amount of the catalyst is notsufficient for accelerating the reaction, whereas if the content exceeds20 parts by weight, the amount of the catalyst is not in proportion tothe effect of accelerating the reaction, and a lot of catalyst willremain in the coating composition to deteriorate the property of thecoating film, thus being not preferred.

Temperature and time required for curing the composition of the presentinvention may vary depending on the temperature at which a free hydroxylgroup or a free carboxyl group is regenerated from the blockedfunctional groups represented by the formulae (1) to (3) kind of theepoxy group optionally contained, or kind of the thermal latent acidcatalyst. However, the curing is usually completed by heating thecomposition at a temperature within the range of from 60 to 300° C. for5 seconds to 24 hours.

The composition of the present invention may be used as it is or,according to the need, as a mixture with a variety of additives such ascoloring pigments, fillers, solvents, UV adsorbents, antioxidants, orflow controlling agents, for a wide range of usage such as coatingmaterials, inks, adhesives, or molded products, utilizing the curingproperty.

The present composition may be prepared by mixing the above componentstogether, and optionally mixing with a variety of additives, ifnecessary. The method of mixing the components and adding the variety ofadditives is not particularly limited, and may be selected from avariety of methods. The order of mixing and adding may also be selectedsuitably.

The coating composition of the present invention may be used as asingle-layered top coating material or as a coating material forpreparing articles having a plurality of coating film layers composed ofa colored base coating film and a clear top coating film. The coatingcomposition of the present invention is quite useful as coatingmaterials for automobiles, coating materials for metal products used aspre-coating or post-coating materials for railway vehicles, or coatingmaterials for electrical appliances, steel structures, machinery,building materials, insulation, moisture-proofing, and rust-preventionof electrical and electronic parts, and other industrial coatings.

In the case of such coating materials, the content of the pigment ispreferably 0 to 300 parts by weight, more preferably 0 to 100 parts byweight based on 100 parts by weight of the reactive resins in thecomposition.

The pigments may include organic and inorganic pigments. In particular,metallic pigments such as surface treated aluminum, copper, brass,bronze, or stainless steel; iron oxides of mica form, metallic powdersof flake form, or titanium oxide; or mica coated with iron oxide may beused. Further, inorganic pigments such as titanium dioxide, iron oxides,yellow iron oxide, or carbon black; organic pigments such asphthalocyanine blue, phthalocyanine green, or quinacridone red pigments;or fillers such as precipitated barium sulfate, clay, silica, or tarcmay also be used.

The coating composition of the present invention may be utilized in amethod for applying composite coating films on an article including thesteps of applying a colored film forming composition on a substrate toform a base coating film, and applying a clear film forming compositionon the base coating film to form a clear top coating film. The coatingcomposition of the present invention may be used as the clear filmforming composition for forming the top coating film, or both the clearfilm forming composition for forming the top coating film and thecolored film forming composition in this method.

Using the coating composition of the present invention in the method ofpreparing a coated product having a plurality of coated films composedof colored base coating film and clear top coating film, excellentappearance of the finished coating may be achieved.

The film forming composition for the colored base coating film includesa resin binder and pigments. The resin binder may be the coatingcomposition of the present invention, or other binders of various kindssuch as well known acrylic polymers, polyester (including alkyd resins),polyurethane, or melamine resins.

Conventionally used additives of various kinds such as surface activeagents, UV adsorbents, levelling agents, thixotropic agents, fillers,defoaming agents, organic solvents, or catalysts may be added to thefilm forming composition for the colored base coating film.

The film forming composition for the clear top coating film may beprepared with the coating composition of the present invention,optionally mixed with the above pigments, various kinds of additives,and dyes having superior weatherability to the extent that thetransparency of the composition is not lowered.

Kind of the substrate on which the coating composition is applied is notparticularly limited, and various kinds of substrate materials includingorganic and inorganic materials such as wood, glass, metal, fabric,plastics, foamed materials, elastomers, paper, ceramics, concrete, orgypsum boards may be used.

Examples of suitable methods for applying the coating compositioncontaining the thermosetting composition of the present invention mayinclude a method including the steps of adjusting the viscosity of thecoating composition by heating or admixing with an organic solvent orreactive thinner depending on the need; applying the thus obtainedcoating composition using a conventional coater such as an air spray, anelectrostatic air spray, a roll coater, a flow coater, or a dipping typecoater, a brush, a bar coater, or an applicator, so that the drythickness of the coated film is 0.5 to 300 μm; and curing the coatedcomposition under heating at a temperature within the range of from 50to 300° C. for 5 seconds to 1 hour. When the coating is carried out intwo coat one bake system, the coating composition of the presentinvention may be applied by a method including the steps of diluting thecoating composition for the base coating film with a suitable thinnersuch as an organic solvent into a desired viscosity; applying thediluted composition according to the above method so that the drythickness of the coated film is usually 5 to 40 μm, preferably 7 to 35μm; allowing the coated film to stand at a room temperature to 100° C.for 1 to 20 minutes; subsequently applying the coating composition forthe clear top coating film prepared with the thermosetting compositionof the present invention according to the above method so that the drythickness of the coated film is 10 to 100 μm, preferably 10 to 60 μm;and curing the coated film under heating at 50 to 300° C. for 5 secondsto 1 hour. The most preferred coating method among those listed above isthe spray coating.

The coated products which may be obtained by applying the coatingcomposition of the present invention may include structures, woodenproducts, metallic products, plastic products, rubber products, coatedpapers, ceramic products, and glass products. Specifically, automobiles,metal plates such as steel plates, two wheelers, ships, railwayvehicles, aircrafts, furniture, musical instruments, domesticappliances, building materials, containers, office supplies, sportsinstruments, and toys may be included.

The thermosetting composition of the present invention gives curedproducts having excellent chemical and physical properties as well asweatherability, and is superior in storage stability, and thus issuitably used for coating materials, inks, adhesives, or moldedproducts. In particular, when the thermosetting composition of thepresent invention is used as a top coating material, discharge of theorganic solvent may be reduced, and excellent appearance may be given tothe finished coating film, thus being quite useful in the field ofindustrial coatings such as coating of automobiles. The thermosettingcomposition of the present invention has, when it is used for thecoating composition, superior storage stability, thermosettingreactivity, abrasion resistance, and acid resistance.

EXAMPLES

The present invention will now be explained with reference to Examples.But the present invention is not limited thereto. The properties of thecoating film in the Examples were determined as follows:

(1) Acid resistance

On a test piece, 2 ml of 40 wt% sulfuric acid was applied as spots, andcondition of the coating film was visually observed after heating at 60°C. for 30 minutes.

(2) Impact resistance

A test piece was clamped to an impact frame of 6.35 mm radius and aweight of 500 g was dropped from the height of 40 cm onto the testpiece, using an impact tester (Japanese Industrial Standard K-5400(1994), 8.3.2., Du Pont method). Damage on the coating film was visuallyobserved.

(3) Weatherability

A test piece was exposed for 1000 hours or 3000 hours, and then 60degree specular gloss (Japanese Industrial Standard K-5400 (1990), 7.6specular gloss) of the coating film was measured, using a sunshineweathermeter (Japanese Industrial Standard K-5400 (1990), 9.8.1).Condition of the coating film was visually observed, or compared withthe condition before the exposure by using the measured values of gloss.

(4) Abrasion resistance

A test piece was fixed on the outer surface of the ceiling of a vehicle,and the vehicle was subjected to machine wash. The abrasion on the testpiece due to the friction of the washing brush was visually observed andevaluated. The car wash was repeated twenty times.

(5) Pencil hardness

Hardness of the coated film was determined in accordance with JapaneseIndustrial Standard K-5400 (1994), 8.4.2.

Preparation Example 1 Preparation of Compound A-1 Having BlockedCarboxylic Acid

(1) Preparation of polycarboxylic acid

Following materials were charged into a four-necked flask equipped witha thermometer, a reflux condenser, a stirrer, and a dropping funnel, andheated under stirring up to 120° C.

    ______________________________________                                        pentaerythritol      136.0  parts by weight                                     methyl isobutyl ketone 538.7 parts by weight                                ______________________________________                                    

Next, 672.0 parts by weight of methylhexahydrophthalic anhydride wasadded dropwise over 2 hours to the starting mixture while thetemperature of the mixture was kept at 120° C., and the resultingmixture was continuously stirred under heating until the acid value ofthe mixture became 170 or less (determined by diluting the mixture 50folds by weight with a 9:1 mixed solution of pyridine and water, heatingthe diluted mixture at 90° C. for 30 minutes, and titrated with astandard solution of potassium hydroxide), thereby obtaining a solutionof a tetra functional polycaroxylic acid compound.

(2) Preparation of compound having blocked carboxylic acid

Using the solution of the polycarboxylic acid compound obtained above, amixture having the following composition was charged in a flask as usedabove and stirred while the temperature of the mixture was kept at 50°C.

    ______________________________________                                        Solution of polycarboxylic                                                                         336.7  parts by weight                                     acid compound obtained in (1)                                                 Isobutyl vinyl ether 120.2 parts by weight                                    35 weight % hydrochloride acid 0.2 parts by weight                            methyl isobutyl ketone 46.3 parts by weight                                 ______________________________________                                    

The reaction was terminated when the acid value of the mixture became 12or less. After the mixture was allowed to cool, the obtained product wastransferred to a separating funnel. The product was subjected to alkaliwashing with 100 parts by weight of a 10 weight % aqueous solution ofsodium carbonate in the separating funnel, and then washing repeatedlywith 300 parts by weight of deionized water until the pH of the washingsolution became 7 or lower. Subsequently, the resulting organic layerwas dried by adding Molecular Sieve 4A1/16 and being left at roomtemperature for 3 days, thereby obtaining Compound A-1 having theproperties as shown in Table 1.

Preparation Example 2 Preparation of Compound B-1 Having BlockedCarboxylic Acid and Blocked Hydroxyl Group

(1) Preparation of polycarboxylic acid

Following materials were charged into a four-necked flask equipped witha thermometer, a reflux condenser, a stirrer, and a dropping funnel, andheated under stirring up to 120° C.

    ______________________________________                                        pentaerythritol      136.0  parts by weight                                     methyl isobutyl ketone 402.0 parts by weight                                ______________________________________                                    

Next, 462.0 parts by weight of hexahydrophthalic anhydride was addeddropwise over 2 hours to the starting mixture while the temperature ofthe mixture was kept constant at 120° C., and the resulting mixture wascontinuously stirred under heating until the acid value of the mixturebecame 170 or less (determined by diluting the mixture 50 folds byweight with a 9:1 mixed solution of pyridine and water, heating thediluted mixture at 90° C. for 30 minutes, and titrated with a standardsolution of potassium hydroxide), thereby obtaining a solution oftrifunctional polycarboxylic acid compound.

(2) Preparation of compound having blocked carboxylic acid and blockedhydroxyl group

Using the solution of the polycarboxylic acid compound obtained above, amixture having the following composition was charged in a flask as usedabove and stirred while the temperature of the mixture was kept constantat 50° C.

    ______________________________________                                        Solution of polycarboxylic                                                                         317.3  parts by weight                                     acid compound obtained in (1)                                                 Isopropyl vinyl ether 142.5 parts by weight                                   35 wt% hydrochloric acid 0.2 parts by weight                                  xylene 40.0 parts by weight                                                 ______________________________________                                    

The reaction was terminated when the acid value of the mixture became 12or less. After the mixture was allowed to cool, the obtained product wastransferred to a separating funnel. The product was subjected to alkaliwashing with 100 parts by weight of a 10 weight % aqueous solution ofsodium carbonate in the separating funnel, and then washing repeatedlywith 300 parts by weight of deionized water until the pH of the washingsolution became 7 or lower. Subsequently, the resulting organic layerwas dried by adding Molecular Sieve 4A1/16 and being left at roomtemperature for 3 days, thereby obtaining Compound B-1 having theproperties as shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                         Preparation                                                                            Preparation                                           example 1 example 2                                                         ______________________________________                                        Resin No.          A-1        B-1                                               Average number of blocked carboxylic 4 3                                      acid as functional group                                                      Average number of blocked hydroxyl -- 1                                       group as functional group                                                     Blocking agent isobutyl vinyl isopropyl vinyl                                  ether ether                                                                Properties                                                                             Non-volatile  60%        60%                                            components (wt%).sup.1)                                                       Number average 1150 980                                                       molecular weight.sup.2)                                                    ______________________________________                                         Note:                                                                         .sup.1) nonvolatile components: Dried at 50° C. at 0.1 mmHg for 3      hours.                                                                        .sup.2) Number Average Molecular Weight: Value obtained by measurement by     gel permeation chromatography followed by calculation in terms of             Polystyrene                                                              

Preparation Example 3 Preparation of Compound B-2 Having BlockedHydroxyl Group and Blocked Carboxylic Acid

(1) Preparation of α, β-unsaturated compound M-1

A mixture having the composition as shown in Table 2 was charged in afour-necked flask equipped with a thermometer, a reflux condenser, and astirrer, and stirred for 10 hours at a constant temperature of 50° C.

After the mixture was allowed to cool, the obtained product wastransferred to a separating funnel. The product was subjected to alkaliwashing with 100 parts by weight of a 10 weight % aqueous solution ofsodium carbonate in the separating funnel, and then washing repeatedlywith 200 parts by weight of deionized water until the pH of the washingsolution became 7 or lower. Subsequently, the resulting organic layerwas dried by adding Molecular Sieve 4A1/16 (manufactured by WAKO JUNYAKUCO., LTD.) and being left at room temperature 3 days, thereby obtainingα, β-unsaturated compound M-1 having the content of the effectivecomponents as shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                                 M-1                                                  ______________________________________                                        Composition of                                                                             2-hydroxylethyl methacrylate                                                                    130.0                                            starting material isopropyl vinyl ether 112.0                                 (parts by weight) hyoroquinone monomethyl ether 0.2                            diethyl hexyl phosphate 0.1                                                Content of effective components.sup.1) (wt%)                                                             90.0                                               ______________________________________                                         Note                                                                          .sup.1) : Content of effective components was determined by gas               chromatography.                                                          

(2) Preparation of α, β-unsaturated compound M-2

A mixture having the composition as shown in Table 3 was charged in afour-necked flask equipped with a thermometer, a reflux condenser, and astirrer, and stirred for 10 hours at a constant temperature of 50° C.After the mixture was allowed to cool, the obtained product wastransferred to a separating funnel. The product was subjected to alkaliwashing with 100 parts by weight of a 10 weight % aqueous solution ofsodium carbonate in the separating funnel, and then washing repeatedlywith 200 parts by weight of deionized water until the pH of the washingsolution became 7 or lower. Subsequently, the resulting organic layerwas dried by adding Molecular Sieve 4A1/16 (manufactured by WAKO JUNYAKUCO., LTD.) and being left at room temperature 3 days, thereby obtainingα, β-unsaturated compound M-2 having the content of the effectivecomponents as shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                                 M-2                                                  ______________________________________                                        Composition of                                                                             methacrylic acid  86.0                                             starting material isopropyl vinyl ether 103.3                                 (parts by weight) hydroquinone monomethyl ether 0.2                            diethyl hexyl phosphate 0.1                                                Content of effective components.sup.1) (wt%)                                                             95.0                                               ______________________________________                                         Note                                                                          .sup.1) : Content of effective components was determined by gas               chromatography                                                           

(3) Preparation of compound having blocked carboxylic acid and blockedhydroxyl group

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 4, andheated under stirring up to 80° C. and sustained. At the constanttemperature of 80° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 4(dropping components) was added dropwise at a constant rate from thedropping funnel over 2 hours, and kept at 80° C. for another hourfollowing completion of the adding. After that, a polymerizationinitiator solution having the composition as shown in Table 4(additional catalyst) was added to the mixture. The mixture was kept at80° C. for 4 hours until the end of the reaction, thereby obtainingCompound B-2 having the properties as shown in Table 4.

Preparation Example 4 Preparation of Compound B-3 Having BlockedCarboxylic Acid and Blocked Hydroxyl Group

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 4, andheated under stirring up to 80° C. and sustained. At the constanttemperature of 80° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 4(dropping components) was added dropwise at a constant rate from thedropping funnel over 2 hours, and kept at 80° C. for another hourfollowing completion of the adding. After that, a polymerizationinitiator 5 solution having the composition as shown in Table 4(additional catalyst) was added to the mixture. The mixture was kept at80° C. for 4 hours until the end of the reaction, thereby obtainingCompound B-3 having the properties as shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                                Preparation                                             example                                                                                               3      4                                            ______________________________________                                        Resin No.                 B-2    B-3                                            xylene (parts by weight) 16.4 15.8                                          Dropping  α, β-Unsaturated Compound M-1                                                          7.2    14.2                                       components α, β-Unsaturated Compound M-2 32.6 32.6                 (parts by n-butyl acrylate 7.6 4.2                                            weight) 2-ethylhexyl methacrylate 15.0 12.0                                    2,2'-azobisisobutylonitrile 3.0 3.0                                           n-butyl acetate 15.0 15.0                                                    Additional n-butyl acetate 3.0 3.0                                            catalyst 2,2'-azobisisobutylonitrile 0.2 0.2                                  (parts by                                                                     weight)                                                                       Property non-volatile components (wt%).sup.1) 60.5 60.6                       Property Number Average Molecular Weight 9800 10200                         ______________________________________                                         Note                                                                          .sup.1) : nonvolatile components: dried at 50° C. at 0.1 mmHg for      hours                                                                         .sup.2) : Number Average Molecular Weight: Value obtained by measurement      by gel permeation chromatography followed by calculation in terms of          polystyrene                                                              

Preparation Example 5 Preparation of Compound C-1 Having Epoxy Aroup

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 5, andheated under stirring up to 140° C. and sustained. At the constanttemperature of 140° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 5(dropping components) was added dropwise at a constant rate from thedropping funnel over 2 hours, and kept at 120° C. for additional twohours following completion of the adding. After that, a polymerizationinitiator solution having the composition as shown in Table 5(additional catalyst) was added to the mixture. The mixture was kept at120° C. for additional 2 hours until the end of the reaction, therebyobtaining Compound C-1 having the properties as shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                                   Prepar-                                              ation                                                                         Ex-                                                                           ample                                                                         5                                                                           ______________________________________                                        Resin No.                    C-1                                                xylene (parts by weight) 37.4                                               Dropping components                                                                        glycidyl methacrylate                                                                             25.6                                           (parts by weight) butyl methacrylate 10.8                                      methyl methacrylate 3.0                                                       2-ethylhexyl methacrylate 20.6                                                Perbutyl O.sup.2) 1.4                                                        Additional catalyst xylene 1.0                                                (parts by weight) Perbutyl O.sup.2) 0.2                                       Property Non-volatile components (wt%).sup.1) 60.0                            Property Number average molecular 11000                                        weight.sup.3)                                                              ______________________________________                                         Note                                                                          .sup.1) nonvolatile components: dried at 50° C. at 0.1 mmHg for 3      hours                                                                         .sup.2) Perbutyl O: trade name, manufactured by NOF CORPORATION, peroxide     .sup.3) Number Average Molecular Weight : Value obtained by measurement b     gel permeation chromatography followed by calculation in terms of             polystyrene.                                                             

Preparation Examples 6 and 7 Preparation of Compounds D-1 and D-2 HavingBlocked Hydroxyl Group and Epoxy Group

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 6, andheated under stirring up to 140° C. and sustained. At the constanttemperature of 140° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 6(dropping components) was added dropwise at a constant rate from thedropping funnel over 2 hours, and kept at 120° C. for 2 hours followingcompletion of the adding. After that, a polymerization initiatorsolution having the composition as shown in Table 6 (additionalcatalyst) was added to the mixture. The mixture was kept at 120° C. for2 hours until the end of the reaction, thereby obtaining Compound D-1and D-2 having the properties as shown in Table 6, respectively.

                  TABLE 6                                                         ______________________________________                                                               Preparation                                              Example                                                                                              6       7                                            ______________________________________                                        Resin No.                D-1     D-2                                            xylene (parts by weight) 36.7 36.7                                          Dropping components                                                                       glycidyl methacrylate                                                                          25.6    29.8                                       (parts by weight) M-1 7.2 7.2                                                  butyl methacrylate 5.9 5.7                                                    2-ethylhexyl methacrylate 22.0 18.0                                           Perbutyl O.sup.2) 1.4 1.4                                                    Additional catalyst xylene 1.0 1.0                                            (parts by weight) Perbutyl O.sup.2) 0.2 0.2                                   Property Non-volatile Components 60.2 60.4                                     (wt%).sup.1)                                                                 Property Number average molecular 12000 11000                                  weight.sup.3)                                                              ______________________________________                                         Note                                                                          .sup.1) nonvolatile components: dried at 50° C. at 0.1 mmHg for 3      hours                                                                         .sup.2) Perbutyl O: trade name, manufactured by NOF CORPORATION, peroxide     .sup.3) Number Average Molecular Weight: Value obtained by measurement by     gel permeation chromatography followed by calculation in terms of             polystyrene                                                              

Preparation Example 8 Preparation of Compound E Having Blocked HydroxylGroup, Blocked Carboxylic Acid, and Epoxy Group

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 7, andheated under stirring up to 80° C. and sustained. At the constanttemperature of 80° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 7(dropping components) was added dropwise at 5 a constant rate from thedropping funnel over 2 hours, and kept at 80° C. for another hourfollowing completion of the adding. After that, a polymerizationinitiator solution having the composition as shown in Table 7(additional catalyst) was added to the mixture. The 10 mixture was keptat 80 C for 4 hours until the end of the reaction, thereby obtainingCompound E having the properties as shown in Table 7.

                  TABLE 7                                                         ______________________________________                                                                   Prepar-                                              ation                                                                         Ex-                                                                           ample                                                                         8                                                                           ______________________________________                                        Resin No.                    E                                                  xylene (parts by weight) 17.0                                               Dropping components                                                                       α, β-unsaturated compound M-1                                                           7.2                                            (parts by weight) α, β-unsaturated compound M-2 21.7                                                glycidyl methacrylate 17.0                    n-butyl methacrylate 5.9                                                      2-ethylhexyl methacrylate 10.0                                                2,2'-azobisisobutyronitrile 3.0                                               butyl acetate 15.0                                                           Additional catalyst butyl acetate 3.0                                         (parts by weight) 2,2'-azobisisobutyronitrile 0.2                             Property Non-volatile components (wt%).sup.1) 60.4                            Property Number average molecular weight.sup.2) 12000                       ______________________________________                                         Note                                                                          .sup.1) : nonvolatile components: dried at 50° C. at 0.1 mmHg for      hours                                                                         .sup.2) Number Average Molecular Weight: Value obtained by measurement by     gel permeation chromatography followed by calculation in terms of             polystyrene                                                              

Preparation Example 9 Preparation of compound F-1 Having BlockedHydroxyl Group

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, an initial charge ofsolvent (xylene) was charged in an amount as shown in Table 8, andheated under stirring up to 80° C. and sustained. At the constanttemperature of 80° C., a mixture containing the monomers and apolymerization initiator having the composition as shown in Table 8(dropping components) was added dropwise at a constant rate from thedropping funnel over 2 hours, and kept at 80° C. for another hourfollowing completion of the adding. After that, a polymerizationinitiator solution having the composition as shown in Table 8(additional catalyst) was added to the mixture. The mixture was kept at80° C. for 4 hours until the end of the reaction, thereby obtainingCompound F-1 having the properties as shown in Table 8.

                  TABLE 8                                                         ______________________________________                                                                   Prepar-                                              ation                                                                         Ex-                                                                           ample                                                                         9                                                                           ______________________________________                                        Rein No.                     F-1                                                xylene (parts by weight) 14.5                                               Dropping components                                                                       α, β-unsaturated compound M-1                                                           43.2                                           (parts by weight) α, β-unsaturated compound M-2 --                  n-butyl methacrylate 15.0                                                     2-ethylhexyl methacrylate 6.1                                                 2,2'-azobisisobutyronitrile 3.0                                               butyl acetate 15.0                                                           Additional catalyst butyl acetate 3.0                                         (parts by weight) 2,2'-azobisisobutyronitrile 0.2                             Property Non-volatile components (wt%).sup.1) 60.4                            Property Number average molecular weight.sup.2) 11000                       ______________________________________                                         Note                                                                          .sup.1) nonvolatile components: dried at 50° C. at 0.1 mmHg for 3      hours                                                                         .sup.2) Number Average Molecular Weight: Value obtained by measurement by     gel permeation chromatography followed by calculation in terms of             polystyrene                                                              

Preparation Example 10 Preparation of compound A-2 Having PolycarboxylicAcid

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, the following componentswere charged, and heated up to 120° C. under stirring.

Pentaerythritol 136.0 parts by weight

methyl isobutyl ketone 538.7 parts by weight

Next, 672.0 parts by weight of methylhexahydrophthalic anhydride wasadded dropwise over 2 hours to the starting mixture while thetemperature of the resulting mixture was kept constant at 120° C., andthe mixture was continuously stirred under heating until the acid valueof the mixture became 170 or less (determined by diluting the mixture 50folds by weight with a 9 : 1 mixed solution of pyridine and water,heating the diluted mixture at 90° C. for 30 minutes, and titrated witha standard solution of potassium hydroxide), thereby obtaining asolution of tetra functional polycarboxylic acid compound having theproperties as shown in Table 9.

                  TABLE 9                                                         ______________________________________                                                                  A-2                                                 ______________________________________                                        Properties of                                                                             Average number of functional groups                                                               4                                               polycarboxylic Acid equivalent (g/mol) 336.7                                  acid compound                                                                 Property.sup.1) Non-volatile components (wt%) 60.0                          ______________________________________                                         Note                                                                          .sup.1) nonvolatile components: dried at 50° C. at 0.1 mmHg for 3      hours                                                                    

Preparation Example 11 Preparation of Thermal Latent Acid Catalyst G-1

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, 25.0 parts by weight ofzinc octylate and 180 parts by weight of triethyl phosphate werecharged, and stirred at room temperature. After the stirring at the roomtemperature for 5 hours, a thermal latent acid catalyst solution G-1 wasobtained.

Preparation Examples 12 and 13 Preparation of Thermal Latent AcidCatalyst G-2 and G-3

Into a four-necked flask equipped with a thermometer, a refluxcondenser, a stirrer, and a dropping funnel, a solvent, Lewis acid, andLewis base as shown in Table 10 were charged, and stirred at 50° C. for2 hours. After the mixture was allowed to cool down to the roomtemperature, the mixture was further stirred for about 1 hour, therebyobtaining thermal latent acid catalyst solutions G-2 and G-3 as shown inTable 10, respectively.

                  TABLE 10                                                        ______________________________________                                                                 Preparation                                            Example                                                                                                12     13                                          ______________________________________                                        Thermal latent catalyst No.                                                                              G-2    G-3                                         Mixing ratio                                                                           Solvent    butyl acetate  69.1 71.6                                    (parts by Lewis base di-n-hexyl sulfide 30.9 --                               weight)  tri-n-butylamine --  28.4                                             Lewis acid methyl ethyl ketone 100.0 100.0                                     solution containing                                                           20.9 wt% zinc chloride                                                    Concentration of solution (% by weight)                                                                  25.9   24.6                                        ______________________________________                                    

Examples 1 to 8 Application to Two Coat One Bake Metallic Color CoatingMaterial

(1) Preparation of clear coating material Starting materials having thecomposition as shown in Tables 11 and 12 were mixed, thereby obtainingone component clear coating materials.

(2) Preparation of test piece and study of coating film propertiesCationic electrodeposition paint AQUA No. 4200 (trade name, manufacturedby NOF CORPORATION) was electrodeposited on a soft steel plate treatedwith zinc phosphate for forming a film having the dry thickness of 20μm, and baked at 175° C. for25minutes. Next, primer surfacer EPICO No.1500 CP Sealer (trade name, manufactured by NOF CORPORATION) was appliedover the previously formed film by air spraying for forming a filmhaving the dry thickness of 40 μm, and baked at 140° C. for 30 minutes.Subsequently, silver metallic base coating material BELCOAT No. 6000(trade name, manufactured by NOF CORPORATION) was applied over thepreviously formed film by air spraying in two stages at an interval of 1minute and 30 seconds for forming a film having the dry thickness of 15μm, and set at 20° C. for 3 minutes, thereby obtaining a test plate.Further, each of the clear coating material prepared in (1) above wasdiluted with a thinner (xylene) into an appropriate viscosity forcoating (25 seconds at 20° C. using Ford Cup No. 4), applied over thetest plate prepared above by air spraying, respectively, and baked at140° C. for 30 minutes, thereby obtaining test pieces.

The properties of the obtained coating films are shown in Tables 11 and12. In all cases, uniform coating films with glossy surface wereobtained. The coating films exhibited excellent acid resistance, impactresistance, weatherability, abrasion resistance, and hardness, when theyhad been baked at 140° C.

(3) Study of storage stability

Each of the clear coating materials prepared in (1) above was dilutedwith a thinner (xylene) into 1 poise (as measured at 20° C. with aBrookfield type viscometer), and stored in a sealed state at 40° C.After the storage at 40 C for 30 days, the viscosity of the clearcoating materials was measured again. As a result, it was revealed thatlittle increase in the viscosity was observed as shown in Tables 11 and12, which showed excellent storage stability of the coating materials.

                                      TABLE 11                                    __________________________________________________________________________                         Example 1                                                                           Example 2                                                                           Example 3                                                                           Example 4                              __________________________________________________________________________    Mixing ratio of                                                                       Compound A-1 426.3 461.6 --    --                                       coating Compound B-1 -- -- -- --                                              materials Compound B-2 -- -- 447.1 --                                          Compound B-3 -- -- -- 447.1                                                   Compound C-1 -- -- 446.8 446.8                                                Compound D-1 470.6 -- -- --                                                   Compound C-2 -- 436.8 -- --                                                   Compound E -- -- -- --                                                        Compound G-1 -- -- -- --                                                      Compound G-2 45.3 44.7 46.7 46.7                                              Compound G-3 -- -- -- --                                                     Concentration of Concentration of epoxy group 1.57 1.70 1.50 1.50                                                   functional Blocked carboxylic                                                acid 1.57 1.70 1.50 1.50                 groups in resin Blocked hydroxyl group 0.26 0.24 0.25 0.50                    (mol/kg)                                                                    Blocked carboxylic acid/Epoxy group                                                                1.0   1.0   1.0   1.0                                      (mole ratio)                                                                  Blocked hydroxyl group/Epoxy group 0.17 0.14 0.17 0.33                        (mole ratio)                                                                Storage Initial viscosity (poise)                                                                  1.0   1.0   1.0   1.0                                      stability (40° C.) Viscosity after 30 days 1.3 1.3 1.4 1.3                                                    (poise)                                Properties of Acid resistance good good good good                             coating film Impact resistance good good good good                             Weatherability.sup.1) 96% 96% 94% 98%                                         Abrasion resistance.sup.2) ◯ ◯ ◯                                              ◯                             Pencil hardness after baking H H F H                                          at 140° C. for 20 min.                                              __________________________________________________________________________     Note .sup.1) Weatherability: The test piece was exposed for 1000 hours,       and then 60 degree specular gloss (Japanese Industrial Standard K5400         (1990), 7.6 specular gloss) of the coating film was measured, using a         sunshine weathermeter (Japanese Industrial Standard K5400 (1990), 9.8.1),     and compared with the specular gloss before the exposure.                     .sup.2) Abrasion resistance: ◯ . . . Little abrasion              Δ . . . Some abrasion                                                   X . . . Remarkable abrasion                                              

Example 9 Application to One Coat Solid Color Coating Material

(1) Preparation of coating material

Staring materials having the composition as shown in Table 13 weremixed, charged into a sand mill, and dispersed until the particle sizeof the solid components became 10 μm or less, thereby obtaining a onecomponent coating material.

(2) Preparation of test piece and study of coating film properties

Cationic electrodeposition paint AQUA No. 4200 (trade name, manufacturedby NOF CORPORATION) was electrodeposited on a soft steel plate treatedwith zinc phosphate for forming a film having the dry thickness of 20μm, and baked at 175° C. for 25 minutes. Next, primer surfacer EPICO No.1500 CP Sealer (trade name, manufactured by NOF CORPORATION) was appliedover the previously formed film by air spraying for forming a filmhaving the dry thickness of 40 um, and baked at 140° C. for 30 minutes,thereby obtaining a test plate. Subsequently, the raw coating materialprepared in (1) above was diluted with a thinner (xylene) into anappropriate viscosity for coating (flow rate of 25 seconds at 20° C.using Ford Cup No. 4), applied over the test plate obtained above by airspraying, and baked at 140° C. for 30 minutes, thereby obtaining a testpiece.

The properties of the obtained coating film are shown in Table 13. Inall cases, a uniform coating film with glossy surface was obtained. Thecoating film exhibited excellent acid resistance, impact resistance,weatherability, abrasion resistance, and hardness, when it had beenbaked at 140° C.

(3) Study of storage stability

The raw coating material prepared in (1) above was diluted with athinner (xylene) into 1 poise (as measured at 20° C. with a Brookfieldtype viscometer) , and stored in a sealed stated at 40° C. After thestorage at 40° C. for 30 days, the viscosity of the coating material wasmeasured again. As a result, it was revealed that little increase in theviscosity was observed as shown in Table 13, which showed excellentstorage stability of the coating material.

                  TABLE 13                                                        ______________________________________                                                                Example 9                                             ______________________________________                                        Mixing ratio of                                                                            Compound C-1     349.0                                             Coating materials Compound B-2 283.0                                          (parts by weight) Compound G-3 33.0                                            titanium dioxide.sup.1) 335.0                                                Concentration of concentration of epoxy group 1.50                            functional groups blocked carboxylic acid 1.50                                in resin (mol/kg) blocked hydroxyl group 0.25                               Blocked carboxylic acid / epoxy group (mole ratio)                                                      1.0                                                   Blocked hydroxyl group / epoxy group (mole ratio) 0.17                      Storage stability                                                                          Initial viscosity (poise)                                                                      1.0                                               (40° C.) Viscosity after 30 days (poise) 1.2                           Properties of Acid resistance good                                            coating film Impact resistance good                                            Weatherability.sup.2) 95%                                                     Abrasion resistance.sup.3) ◯                                      Pencil hardhess after baking at H                                             140° C. for 20 min.                                                 ______________________________________                                         Note                                                                          .sup.1) Titanium dioxide JR602: trade name, manufactured by TEIKOKU KAKO      CO., LTD., rutile type titanium dioxide                                       .sup.2) Weatherability: measured in the same method as for Table 11           .sup.3) Abrasion resistance: evaluated in the same method as for Table 11

Comparative Examples 1 to 5

Coating materials were prepared in accordance with the composition shownin Table 14, coated articles were produced, and each test was conductedin the same way as in Examples 1 to 8. The results are shown in Table14.

From the results shown in Table 14, it was revealed that the coatingfilm of Comparative Example 1 was superior in acid resistance, impactresistance, weatherability, and hardness, but inferior in abrasionresistance. The coating films of Comparative Examples 2 and 3 hadinsufficient hardness. The coating material of Comparative Example 4gelled after 10 days of storage since the functional groups, i.e. thecarboxyl group and the epoxy group, were not blocked in thecross-linking reaction therebetween. The coating material of ComparativeExample 5 gelled after 1 day of storage since this material did notcontain the thermal latent catalyst.

                                      TABLE 12                                    __________________________________________________________________________                         Example 5                                                                           Example 6                                                                           Example 7                                                                           Example 8                              __________________________________________________________________________    Mixing ratio of                                                                       Compound A-1 --    --    489.5 --                                       coating Compound B-1 436.2 462.2 -- --                                        materials Compound B-2 -- -- -- --                                             Compound B-3 -- -- -- --                                                      Compound C-1 462.9 490.8 -- --                                                Compound D-1 -- -- -- --                                                      Compound D-2 -- -- 463.1 --                                                   Compound E -- -- -- 952.6                                                     Compound G-1 100.9 -- -- --                                                   Compound G-2 -- -- 47.4 47.4                                                  Compound G-3 -- 47.1 -- --                                                   Concentration of Concentration of epoxy group 1.54 1.54 1.70 2.00                                                   functional Blocked carboxylic                                                acid 1.54 1.54 1.70 2.00                 groups in resin Blocked hydroxyl group 0.51 0.51 0.24 0.50                    (mol/kg)                                                                    Blocked carboxylic acid/Epoxy group                                                                1.0   1.0   1.0   1.0                                      (mole ratio)                                                                  Blocked hydroxyl group/Epoxy group 0.33 0.33 0.14 0.25                        (mole ratio)                                                                Storage Initial viscosity (poise)                                                                  1.0   1.0   1.0   1.0                                      stability (40° C.) Viscosity after 30 days 1.5 1.3 1.3 1.3                                                    (poise)                                Properties of Acid resistance good good good good                             coating film Impact resistance good good good good                             Weatherability.sup.1) 94% 95% 98% 93%                                         Abrasion resistance.sup.2) ◯ ◯ ◯                                              ◯                             Pencil hardness after baking F F H F                                          at 140° C. for 20 min.                                              __________________________________________________________________________     Note .sup.1) Weatherability: The test piece was exposed for 1000 hours,       and then 60 degree specular gloss (Japanese Industrial Standard K5400         (1990), 7.6 specular gloss) of the coating film was measured, using a         sunshine weathermeter (Japanese Industrial Standard K5400 (1990), 9.8.1),     and compared with the specular gloss before the exposure.                     .sup.2) Abrasion resistance: ◯ . . . Little abrasion              Δ . . . Some abrasion                                                   X . . . Remarkable abrasion                                              

                                      TABLE 14                                    __________________________________________________________________________                         Comp. Ex. 1                                                                         Comp. Ex. 2                                                                         Comp. Ex. 3                                                                         Comp. Ex. 4                                                                         Comp. Ex. 5                      __________________________________________________________________________    Mixing ratio of                                                                       Compound A-1 470.6 --    --    --    426.3                              coating Compound A-2 -- -- -- 273.1 --                                        materials Compound B-1 -- -- 465.0 -- --                                       Compound C-1 426.4 470.0 -- 606.9 --                                          Compound C-2 -- -- -- -- --                                                   Compound D-1 -- -- -- -- 470.6                                                Compound F-1 -- 480.0 485.0 -- --                                             Butylacetate solution -- -- -- -- 45.3                                        containing 10.4% ZnCl.sup.2                                                   Compound G-1 103.0 -- -- 120.0 --                                             Compound G-2 -- 50.0 50.0 -- --                                              Concentration of Concentration of epoxy group 1.74 1.5 0 2.07 1.57                                                        functional Blocked carboxyli                                                 c acid 1.74 0 1.5 2.07 1.57                                                    groups in resin Blocked                                                      hydroxyl group 0 1.5 0.75 0                                                   0.26                               (mol/kg)                                                                    Blocked carboxylic acid/Epoxy group                                                                1.0   0     1.0   1.0   1.0                                (mole ratio)                                                                  Blocked hydroxyl group/Epoxy group 0 1.0 -- 0 0.17                            (mole ratio)                                                                Storage Initial viscosity (poise)                                                                  1.0   1.0   --    1.0   1.0                                stability (40° C.) Viscosity after 30 days 1.4 1.1 1.1 gelled                                                     gelled                              (poise)                                                                      Properties of Acid resistance good worse worse good good                      coating film Impact resistance good good good good good                        Weatherability.sup.1) 90% -- -- 85% 92%                                       Abrasion resistance.sup.2) Δ -- -- ◯ ◯                                                      Pencil hardness after                                                       baking F 3B> 3B> H H                                                            at 140° C. for 20                                                    min.                             __________________________________________________________________________     Note .sup.1) Weatherability: The test piece was exposed for 1000 hours,       and then 60 degree specular gloss (Japanese Industrial Standard K5400         (1990), 7.6 specular gloss) of the coating film was measured, using a         sunshine weathermeter (Japanese Industrial Standard K5400 (1990), 9.8.1),     and compared with the specular gloss before the exposure.                     .sup.2) Abrasion resistance: ◯ . . . Little abrasion              Δ . . . Some abrasion                                                   X . . . Remarkable abrasion                                              

What is claimed is:
 1. A thermosetting composition comprising a resinhaving at least one functional group selected from the group consistingof a blocked hydroxyl group, blocked carboxylic acid, and an epoxygroup, said composition having a blocked hydroxyl group, blockedcarboxylic acid, and an epoxy group.
 2. The thermosetting composition asclaimed in claim 1 wherein said resin having at least one functionalgroup selected from the group consisting of a blocked hydroxyl group,blocked carboxylic acid, and an epoxy group is selected from the groupconsisting of an acrylic resin having number average molecular weight of500 to 100000, a polyester resin having number average molecular weightof 500 to 100000, and mixtures thereof.
 3. The thermosetting compositionas claimed in claim 1 wherein said blocked hydroxyl group has astructure represented by the formula selected from the group consistingof formulae (1) and (2) below: ##STR7## wherein R¹ stands for a hydrogenatom or an alkyl group having 1 to 10 carbon atoms, R² stands for analkyl group having 1 to 22 carbon atoms of which hydrogen has beensubstituted or not substituted by at least one member selected from thegroup consisting of a cycloalkyl group, an aralkyl group, an aryl group,an alkoxyl group, an alkanoyloxy group, an alkyl group having 1 to 18carbon atoms, and a halogen atom; ##STR8## wherein X stands for analkylene group having 1 to 18 carbon atoms of which hydrogen has beensubstituted or not substituted by at least one member selected from thegroup consisting of an alkoxyl group, an aralkyl group, an aryl group,an aryloxy group, an alkanoyloxy group, an alkyl group having 1 to 10carbon atoms, and a halogen atom.
 4. The thermosetting composition asclaimed in claim 1 wherein said blocked carboxylic acid has a structurerepresented by the formula (3): ##STR9## wherein R³, R⁴, and R⁵ eachstands for a hydrogen atom or an organic residue having 1 to 18 carbonatoms, R⁶ stands for an organic residue having 1 to 18 carbon atoms,wherein R⁵ and R⁶ may be bound together to form a heterocyclic ringhaving Y as a hetero atom, wherein Y stands for an oxygen or sulfuratom.